In this chapter we have looked at examples of several recursive
algorithms. These algorithms were chosen to expose you to several
different problems where recursion is an effective problem-solving
technique. The key points to remember from this chapter are as follows:

All recursive algorithms must have a base case.

A recursive algorithm must change its state and make progress toward
the base case.

A recursive algorithm must call itself (recursively).

Recursion can take the place of iteration in some cases.

Recursive algorithms often map very naturally to a formal expression
of the problem you are trying to solve.

Recursion is not always the answer. Sometimes a recursive solution
may be more computationally expensive than an alternative algorithm.